• Journal of Plant Biology
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• v.31 no.1
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• pp.41-49
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• 1988

Several cultivars of rice were examined for induction of embryogenic callus on a medium containing MS salts, vitamins and 2, 4-D under darkness. Embryogenic callus was obtained from cultivar Cheonma with high ratio and embryo-like structures were formed from the callus on a medium with or without reduced 2, 4-D. Somatic embryoids with a plumule and radicle axis surrounded by a scutellum were observed. These embryoids germinated and produced plantlets in 30 days on the same medium. Protoplasts isolated from an embryogenic cell suspension culture derived from embryogenic callus were cultured either in liquid or in agar medium and protoplast derived cell colonies were obtained in 3-4 weeks.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.6
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• pp.650-655
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• 1996

In order to investigate the effects of added magnetized water on the callus induction and plant regeneration in rice, 700G(G=Gauss) magnetized water were used. The callus in-duction and plant regeneration of rice in magnetized water treatment are different from the callus induction and plant regeneration in ionic water treatment. The rates of callus induction in magnetized water media were 27.3% in solid media and 15.4% in liquid which were compared to that of callus induction in the ionic water media 21 and 13.3%. Also plant regeneration frequency in the magnetic water media is 5.4% better than that of the ionic water media. And dissolved oxgen amount of magnetic culture media is from 0.1 ppm to 0.9 ppm more than that of ionic culture media. The pH value was increased with rising of water temperature, and the magnetic water was effected at increasing of pH value.

• Plant Resources
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• v.7 no.1
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• pp.39-46
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• 2004

To demonstrate the importance of transformation efficiency in independent event, molecular and cytogenetic analysis were conducted with genomic DNA and chromosome of transgenic plants produced by Agrobacterium tumefeciens LBA4404 (pSBM-PPGN: gusA and bar). Selection ratios of putative transgenic calli were similar in independent experiments, however, transformation efficiencies were critically influenced by the type of regeneration media. MSRK5SS-Pr regeneration mediun, which contains 5 mgL$^{-1}$ kinetin, 2% (w/v) sucrose in combination with 3% (w/v) sorbitol, and 500 mgL$^{-1}$ proline, was efficient to produce transgenic plant of rice from putative transgenic callus in the presence of L-phosphinotricin (PPT). With MSRK5SS-Pr medium, transformation efficincies of Nagdongbyeo were significantly enhanced from 3.7% to 6.3% in independent callus lines arid from 7.3% to 19.7% in plants produced, respectively. Stable integration and expression of bar gene were confirmed by basta herbicide assay, PCR amplification and Southern blotting of bar gene, and fluorescence in situ hybridization (FISH) analysis using pSBM-PPGN as a probe. In Southern blot analysis, diverse band patterns were observed in total 44 transgenic plants regenerated from 20 independent PPT resistant calli showing from one to five copies of T-DNA segments, however, the transformants obtained from one callus line showed the same copy numbers with the same fractionized band patterns.

• Korean Journal of Weed Science
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• v.10 no.4
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• pp.285-293
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• 1990

The response of callus growth of rice (Oryza sativa L.) cultivars which showed different responses to herbicides as seedlings was investigated to select resistant or tolerant calli. Callus growth of IR28 which was susceptible to thiobencarb (S-[(4-chlorophenyl)methyl]diethylcarbamothioate) during callus induction was not inhibited by $10^{-5}$ M and $10^{-6}$ M thiobencarb, indicating that there was a difference in tolerance among callus induction and growth, and the intact plant level. A similar result was obtained with IR31917-45-3-2-2 to butachlor [N - (buthoxymethyl) -2-chloro-N- (2, 6-diethylphenyl) acetamide]. The fresh weight of IR28 callus transferred into $10^{-5}$ M thiobencarb after treatment at $10^{-6}$ M for 30 days was not affected by the herbicide, indicating that transferring callus into gradually higher herbicide concentrations can be a useful method for selection of herbicide-tolerant cell lines.

• Journal of Plant Biotechnology
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• v.5 no.1
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• pp.43-49
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• 2003

Resistant cell lines to azetidine-2-carboxylic acid (AZCA) were selected through rice embryo culture after mutagenic treatment of callus irradiated with 30,50,70,90 and 120 Gy. The optimum AZCA concentration for the selection of resistant cell lines was 3 or 4 mM AZCA considering $LD_{50}$ and the fresh weight of callus. Survival rate of the AZCA resistant callus showed remarkable increase in the callus irradiated with 50 and 70 Gy. Regeneration rate of the AZCA resistant callus was much lower on the whole. Ninety and 120 Gy increased the regeneration rate for calli selected from 3 and 4 mM AZCA, respectively. Based on fresh weight, survival rate and regeneration for selection of the AZCA resistant cell line, 50-90 Gy was considered as the optimum range of gamma irradiation. Irradiated calli selected from AZCA were more tolerant to NaCl than those from non-irradiated calli. It suggests that elevated resistance to osmotic stress resulted from mutagenic treatment. The level of free proline content in the AZCA resistant cell line was increased up to 3.5 times compared with that in the control. Proline content in the regenerant derived from the AZCA resistant cell line also increased to 1.7 times that from the control plants regenerated from callus grown in AZCA free medium. Selection of proline overproducing cell lines by in vitro mutagenesis was successful and seems to be useful for improvement of stress tolerance in this crop.

• Current Research on Agriculture and Life Sciences
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• v.9
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• pp.21-28
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• 1991

The effect of subculture intervals and passages on plant regeneration from seed-derived callus was determined. Regeneration capacity of callus varied with rice cultivars and subculture intervars tested. The callus subcultured every 2 weeks produced more plants than that of 4 weeks. The calli from a Tongil-type rice cultivar, Milyang 23, lost easily their regeneration ability when the calli were subcultured every 2 weeks and 4 weeks. The callus induced from a japonica cultivar, "Yeongdeogbyeo", showed to maintain high frequency(>70%) of plant regeneration when it was subcultured every 2-week intervals. Casein hydrolysate supplemented in callus induction medium enhanced callus growth and its regeneration. High frequency of plant regeneration was obtained from the calli transferred on $N_6$ medium supplemented with kinetin(2mg/1) and NAA(1mg/1). The subcultured calli in the medium supplemented with casein hydrolysate(2 g/1), myo-inositol(200mg/1) and thiamine-HCl(2mg/1) increased the frequency of embryogenic callus formation and plant regeneration.

• Journal of Plant Biotechnology
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• v.5 no.3
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• pp.163-168
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• 2003

A routine system based on particle bombardment of embryogenic callus for recovery of fertile transgenic rice (Oryza sativa L.) plants was developed. Embryogenic callus was established within 2-3 months from calli derived from mature seeds of Korean rice cultivar, Nagdongbyeo. The callus was bombarded with the plasmid pRQ6 containing the $\beta$-glucuronidase gene (gusA) and hygromycin phosphotransferase gene (hph, conferring resistance to hygromycin B), both driven by CaMV 35S promoter. Placement of cells on an osmoticum-containing medium (0.2 M sorbitol and 0.2 M mannitol) 4 hrs prior to and 16 hrs after bombardment resulted in a statistically significant increase with 3.2-fold in transient expression frequency gusA. In five independent experiments, the average frequency of transformation showing GUS activities was $8.86\%$. A large number of morphologically normal, fertile transgenic rice plants were obtained. Integration of foreign gene into the genome of $R_0$ transgenic plants was confirmed by Southern blot analysis. GUS and HPT were detected in $R_1$ progeny and Mendelian segregation of these genes was observed in $R_1$ progeny.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.5
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• pp.335-340
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• 2002

To evaluate the efficiency of anther floating culture according to the maturing group, the varietal difference and classification of fifty varieties was conducted in N6 liquid medium containing 1mg $l^{-1}$ NAA, 0.25 mg $l^{-1}$ kinetin. The efficiency of callus induction was widely ranged from 0 to 113.4%, but the mean callus induction was not significantly different among maturing groups. The efficiency of anther floating culture showed the highest variation in early-maturing group among three maturing groups. The varieties with the best callus induction were Sambaegbyeo and Jinbuolbyeo, while the recalcitrant variety was Obongbyeo in early-maturing group. The efficiency of plant regeneration showed the highest trends in late-maturing group among three maturing groups. The fifty varieties were classified into three groups (distance=0.78) by cluster analysis based on the callus formation and plant regeneration. Group including only two varieties, Shinunbongbyeo and Sambaegbyeo had the excellent androgenic efficiency, and the medium efficiency of Group was included thirty-six varieties. Whereas twelve varieties, including three Tongil varieties were fell into the bad efficiency of Group. Especially, Tongil varieties containing Japonica rice, Obongbyeo were the recalcitrant genotypes for the anther floating culture.

• Journal of Plant Biotechnology
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• v.35 no.2
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• pp.133-140
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• 2008

The modification of DNA and histone plays an important role for gene expression in plant development. The objective of this research is to observe the effects of methylation on the gene expression during dedifferentiation from rice mature seeds to callus and differentiation from callus to shoots. The embryogenic callus with ability to shoot regeneration was not induced on the N6A medium supplemented with 5-azacytidine and abnormal callus with brown color was formed. When the normal rice callus was placed on the regeneration MSRA medium supplemented with 5-azacytidine, the shoot regeneration was inhibited. The results showed that 5-azacytidine, DNA demethylating agent, had negative effects on normal embryogenic callus formation and shoot regeneration. This suggested that DNA methylation of some genes was required for normal cell dedifferentiation and differentiation in tissue culture. The microarray and $GeneFishig^{TM}$ DEG screening were used to observe the gene transcript profile in callus induction and regeneration on N6A (N6 medium + 5-azaC) and MSRA (MS regeneration medium + 5-azaC). Subsets of genes were up-regulated or down-regulated in response to 5-azaC treatments. The genes related with epigenetic regulation, electron transport, nucleic acid metabolism and response to stress were up and down regulated. The different expression of some genes (germin like protein etc.) during callus induction and shoot regeneration was confirmed using RT-PCR and northern blot analysis.

• Korean Journal of Plant Tissue Culture
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• v.27 no.2
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• pp.77-82
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• 2000

This study was conducted to determine the inheritance of the ability of callus formation and plant regeneration in seed cultures of rice. The culturabilities of three Japonica rices,'Chucheongbyeo', 'Nagdongbyeo', and 'Daeribbyeo 1', were higher than those of Tongil type cultivars, 'Milyang 23' and 'Samgangbyeo 'The frequency for callus growth in F₂ populations of the three crosses, 'Milyang 23/Chucheongbyeo', 'Milyang 23/Daeribbyeo 1', and' Samgangbyeo/Nagdongbyeo', revealed a nearly normal distribution. The broad-sense heritability estimated from the ability of callus formation in the crosses were ranged from 83.8% to 90.1%. The frequency distribution of plant regenerability in F₂ population of 'Milyang 23/Daeribbyeo 1' showed a continuous variation. But the segregation mode of plant regenerability from seed-derived callus in the F₂ progenies of 'Milyang 23/Chucheongbyeo' and 'Samgangbyeo/Nagdongbyeo' appeared to fit the expected 3 : 1 ratio for the high and low regenerability. These results suggest that the high plant regenerability of 'Chucheongbyeo' and 'Nagdongbyeo' was regulated by a single dominant gene.